A vinyl acetate-ethylene copolymer emulsion (hereinafter, referred to as a ‘VAE emulsion’) has been widely used in the overall industries, such as for use in paint binder, wood adhesion, carpet back coating, non-woven fabric, construction (waterproof agent, adhesion promoter, and primer), and paper coating.
When the VAE emulsion is produced, various types of initiators (for example, redox types/thermal decomposition) are used, and various additives including a cationic inorganic pigment such as calcium carbonate, carbon black, clay, titanium dioxide, cement, and silica sand, or an organic additive such as a thickener, a plasticizer, and a dispersant are added according to the use thereof. Aggregates occur due to extra initiators or the compatibility problem between residual monomers and various additives in the VAE emulsion. Problem such as abnormal physical properties or a change in viscosity may also occur. The problems result in the deterioration of stability of the VAE emulsion. Further, the VAE emulsion is often used in a mixture with other aqueous emulsions, and in this case, there sometimes occurs a problem with the mixture stability with other emulsions.
Furthermore, since reactions proceed in water during the production of a VAE emulsion, and a final product also contains a large amount of water, the VAE emulsion is exposed to danger of decay. Accordingly, the VAE emulsion generally includes a preservative. Examples of the preservative include 5-chloro-2-methyl-4-isothiazolin-3-one (hereinafter, referred to as ‘CMIT’), 2-methyl-4-isothiazolin-3-one (hereinafter, referred to as ‘MIT’), and 1,2-benzisothiazolin-3-one (hereinafter, referred to as ‘BIT’). However, the preservative is destroyed owing to residual initiators in the VAE emulsion in the art, the pH of a product, the storage temperature, and oxidation-reduction potentials. As a result, the storage stability of a VAE emulsion product is also affected.
In this connection, Korean Patent No. 10-0967591 discloses a composition including 3-isothiazolone and an iodine-containing stabilizer. However, the document does not disclose that the composition is used for the polymerization of a vinyl acetate-ethylene copolymer.